1. Field of the Invention
The present invention relates generally to power status detecting apparatus and, more particularly, is directed to a power status detecting apparatus for use with electric products which use home AC power sources and which are controlled by a remote controller.
2. Description of Related Art
Generally, in equipment which are to be controlled by a remote controller, a power switch is turned ON and OFF by a power control signal from a remote controller. That is, a toggle switch operation is accomplished.
When a user controls various audio-visual apparatus such as a video tape recorder (VTR), a compact disc (CD) player, a laser disc (LD) player, a tuner, a tape deck or the like by utilizing a remote controller, the user observes so as to check if power is ON or OFF on the various units. For example, if initially the power switch of a television receiver is in the OFF state, the user has to depress a power switch of the remote controller for the television receiver so as to turn its power switch ON, and then the user selects a certain television channel to watch.
However, when certain equipment is required to be controlled by the use of a system control apparatus, if its power status is not clear, then the system control apparatus does not know whether a first power source control command should be issued.
To remove this disadvantage, a bidirectional control bus system such as a so-called home bus system have been recently proposed. According to such bidirectional control bus system, the power status of each apparatus can be automatically identified by using bus lines such that a so-called interlocking system operation is possible.
More precisely, when the user wants to play, for example, a video tape recorder, by pushing a play button of a remote controller for the video tape recorder directly, it is possible to automatically turn ON equipments necessary for the playing back operation of the video tape recorder which include, for example, a television monitor receiver, a video tape recorder and an audio amplifier, so that the play operation of the video tape recorder will start. In this case, unnecessary equipments such as a compact disc (CD) player or the like will have their power switches automatically turned OFF.
In old types of equipments which do not have the home bus terminal, however, the systematic control such as described above cannot be accomplished.